
from tkinter import *
root = Tk()
root.title('Canvas')
canvas = Canvas(root, width=400, height=400, bg='white')
x0,y0,x1,y1 = 120, 120, 275, 275
for i in range(19):
    canvas.create_rectangle(x0, y0, x1, y1)
    x0 -= 5
    y0 -= 5
    x1 += 5
    y1 += 5

canvas.pack()
root.mainloop()